Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Digestion of bovine erythrocytes (BE) with trypsin (Tr) or chymotrypsin (CTr) revealed 'Tr and CTr specific' receptors respectively. These receptors reacted with all the isologous, including the autologous, sera. The titres of agglutinability varied for the Tr-digested BE from 1:2 to 1:64 and from zero to 1:128 for the CTr-digested BE. However, the variation between the members of monozygous twin pairs (MZ) in no case exceeded +/- 2 score units, the error limits. Agglutination of the CTr-digested BE gave with the PHA lectin very similar, (r = 0.964) results to that which was obtained with the isologous sera. The titre of agglutinins showed concordance in all the sera of MZ pairs when tested against the neuraminidase-digested human erythrocytes and the Tr or CTr-digested BE. Their variance due to differences varied between MZ pairs from 60.4 to 74.3%.
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PMID:Natural agglutinins to hidden membrane components in the bovine erythrocytes. 689 9

As Dictyostelium discoideum amoebae differentiate from the noncohesive to the mutually cohesive state, they synthesize two galactose-binding lectins--discoidins I and II--which have been implicated as obligatory components of the morphogenetic cell-cell recognition and cohesion system. These proteins have been shown to have similar amino acid compositions and subunit Mr and overlapping but distinct carbohydrate recognition specificities. We have performed extensive immunochemical and biochemical analyses to study the structural relationships between these two molecules and to eventually identify structural and functional domains. Antisera raised against highly purified preparations of discoidin I and discoidin II were tested for their reactivities against each protein by both immunoprecipitation and double diffusion analyses. The patterns of crossreactivity indicated the presence of shared as well as unique antigenic determinants. This interpretation was supported by two-dimensional thin-layer peptide map analysis and by studies with purified peptides. Of approximately 10-12 peptides observed after exhaustive tryptic digestion of each radioiodinated lectin, 3 appeared to be common to both. These putative common peptides were purified, and the corresponding peptides from discoidins I and II were found to behave identically by two-dimensional thin-layer analysis, gel filtration, and susceptibility to chymotrypsin. The finding of common and unique regions in discoidins I and II suggests analogies with other families of recognition proteins and may have important functional implications for these cell-cell recognition molecules.
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PMID:Discoidins I and II: common and unique regions on two lectins implicated in cell--cell cohesion in Dictyostelium discoideum. 704 11

In all of six cases of congenital dyserythropoietic anaemia, type II (HEMPAS), gel electrophoresis in the presence of SDS revealed abnormally rapid migration of the preponderant integral membrane protein, band 3. After proteolysis of intact cells, the remaining part of the band 3, comprising the intramembrane segment and the cytoplasmic domain, migrated electrophoretically as a single band, identical in mobility to that from normal cells treated in the same manner. The anomaly thus resides in the extracellular domain of the protein, which is the glycosylated part of the chain. Peptide digests of the band 3 showed no evidence of a missing protein segment in the abnormal cells and the amino acid composition of the peptides derived from proteolysis of the extracellular protein of intact cells was also normal. We infer that the anomaly is one of glycosylation. The major glycoproteins, detected by carbohydrate-specific (PAS) stain appear normal in SDS gels. However, when the more sensitive procedure of reacting after electrophoresis with radioiodinated lentil lectin is employed, some additional minor protein components are revealed. In particular one species of apparent subunit molecular weight about 150 000 appeared in all cases of HEMPAS examined and in no normals. This component is not accessible to proteolysis by chymotrypsin or Streptomyces griseus protease, and may be associated with the inner membrane patches, characteristic of the HEMPAS condition. Overall cell shape and microviscosity of the membrane bilayer, as measured by fluorescence polarization of a lipid-soluble fluorophore, were substantially normal in HEMPAS cells.
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PMID:Red cell membrane protein anomalies in congenital dyserythropoietic anaemia, type II (HEMP AS). 706 6

To test whether urate crystal-membrane protein interactions mediate platelet stimulation, platelet membrane proteins were radiolabeled by lactoperoxidase, extracted with 1% Triton X-100, and incubated with urate crystals. The crystal-associated and supernate fractions were isolated and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and by 2-dimensional isoelectric focusing followed by SDS-PAGE. Four of the lactoperoxidase-radiolabeled polypeptides that associated with urate crystals had reduced molecular weights and pIs of Mr = 105,000, pI 4.9; Mr = 123,000, pI = 4.9; Mr = 123,000, pI = 5.3; and Mr = 132,000, pI = 4.8-6.3, respectively. These proteins were characterized with regard to their labeling intensities, apparent isoelectric points, apparent molecular weights (reduced and nonreduced), lectin-binding properties, carbohydrate- and protein-staining characteristic, and presence or absence in Glanzmann's thrombasthenia. They have been identified as derived from glycoproteins Ib, IIb, and III (Phillips-Agin nomenclature) and an unidentified membrane protein. To test whether removal of these proteins would result in a diminution of platelet response to urate, intact platelets were digested with chymotrypsin, resulting in cleavage of more than 80% of these proteins and a 5-fold reduction in secretory responsiveness to urate crystals. Response to a second platelet stimulus, collagen, was unaffected, indicating an intact secretory mechanism. In addition, when platelets were preincubated with F(ab')2 fragments of an antibody directed against these proteins, platelet secretory response to urate was inhibited by 50%, whereas the responses to collagen and thrombin were unaffected. Thus, membrane proteins appear to mediate platelet stimulation by urate crystals.
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PMID:The role of cell surface proteins in platelet stimulation by monosodium urate crystals. 708 98

The complete amino acid sequence of the alpha chain of the mitogenic lectin from Vicia sativa has been determined. The polypeptide was digested by trypsin and chymotrypsin. The fragments were isolated and most of them were sequenced by automatic solid-phase Edman degradation. A total sequence of 52 amino acid residues was obtained which is homologous to the alpha subunits of the lectins from Pisum sativum, Lens culinaris and Vicia faba. The central part (residues 13-32) in particular is completely conserved in all four proteins. In contrast to the three other known sequences, the V. sativa alpha subunit has an additional serine at the N terminus. The differences of the related amino acid sequences of these lectins and concanavalin A, the lectin from Canavalia ensiformis, have been compared using the relative substitution frequency found in homologous proteins by McLachlan. The degree of homology decreases in the order: V. sativa greater than P. sativum greater than V. faba greater than L. culinaris greater than C, ensiformis. Prediction of the secondary structure according to Chou and Fasman reveals that the lectin alpha chain is similar to concanavalin A in the first half of the molecule whereas the C-terminal part apparently tends to form an alpha helix.
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PMID:The amino-acid sequence of the alpha subunit of the mitogenic lectin from Vicia sativa. 720 14

The chicken hepatic lectin is involved in the clearance of glycoproteins from circulation (Kawasaki, T., and Ashwell, G. (1977) J. Biol. Chem. 252, 6536-6543). The complete amino acid sequence of chicken hepatic lectin has been established by analysis of peptides generated by chemical cleavage at methionine or tryptophan residues. Larger BrCN fragments were further digested with trypsin, chymotrypsin, and clostripain. All sequences were determined by automated sequential Edman degradation. Extensive use was made of high performance liquid chromatography in the purification of peptides and identification of phenylthiohydantoin derivatives of amino acids. The complete sequence is: (formula: see text). The stretch of uncharged amino acids from residue 25 to 48 is a possible membrane-interaction region. Carbohydrate is attached to residue 67.
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PMID:Complete amino acid sequence of a membrane receptor for glycoproteins. Sequence of the chicken hepatic lectin. 724 Jan 75

The glycoprotein (GP) L-selectin initiates adhesive interactions between leukocytes and endothelial cells (EC). It functions as a lymphocyte-lectin homing receptor recognizing carbohydrate determinants of the peripheral lymph node addressing on high endothelial venules. It also mediates neutrophil rolling, the earliest interaction of neutrophils with acutely inflamed venules. Neutrophil L-selectin presents sialyl-LewisX (sLe(X)) as a ligand to P- and E-selectin in vitro, and we have proposed that this is a major mechanism of L-selectin-mediated rolling in vivo. In contrast, the contribution of neutrophil L-selectin as a receptor protein recognizing one (or more) ligand(s) on inflamed EC is unclear. To address this question, an sLe(X)-negative murine pre-B cell line, L1-2, that can neither bind vascular selectins nor roll in inflamed rabbit venules, was transfected with human L-selectin cDNA. L-selectin expression in stable transfectants was sufficient to confer significant rolling in vivo. Rolling was unaffected by neuraminidase treatment but completely blocked by anti-L-selectin monoclonal antibody (MoAb) DREG-56. Thus, L-selectin can initiate leukocyte interactions with EC determinants potentially through recognition of endothelial carbohydrates. In contrast, when human neutrophils were tested, rolling was reduced, but not abolished, by MoAb DREG-56. Likewise, treatment with neuraminidase or anti-sLe(X) MoAbs decreased, but did not abrogate, neutrophil rolling, consistent with residual EC recognition via L-selectin. Combination of MoAb DREG-56 and neuraminidase resulted in almost complete loss of rolling, as did removal of glycosylated L-selectin by chymotrypsin. Together with the demonstrable rolling of L-selectin transfectants, our results support the concept of a bidirectional interaction between L-selectin bearing sLe(X) on neutrophils and activated EC in vivo. These findings also suggest that L-selectin may mediate rolling of lymphocytes that lack carbohydrate ligands for E- or P-selectin, although probably less efficiently than through bidirectional recognition.
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PMID:L-selectin mediates neutrophil rolling in inflamed venules through sialyl LewisX-dependent and -independent recognition pathways. 768 86

A photoactivatable heterobifunctional fluorescent reagent, 1-azido-5-naphthalene sulfonyl (ANS) hydrazide, was synthesized and characterized. ANS-hydrazide reacted with lactose to form a photoactivatable hydrazone. The derivative (ANS-lactose) had the same binding affinity for a conger eel lectin as lactose judging from the hemagglutinating-inhibition assay with rabbit erythrocytes. ANS-lactose was used for photoaffinity labeling of a conger eel lectin. The photolabeled lectin was digested with chymotrypsin to isolate photolabeled peptides by reversed-phase HPLC by monitoring fluorescence. A major labeled peptide was located at positions 31-45 in the lectin by amino acid analysis and N-terminal sequencing. The identified segment was close to the highly conserved region throughout animal beta-galactoside-binding lectins.
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PMID:Preparation of a photoactivatable fluorescent derivative of lactose and its application to photoaffinity labeling of a conger eel lectin. 776 30

Mannose-binding protein (MBP) plays an important role in host defense by recognizing sugar residues on certain pathogens and activating the complement cascade. Recently, we described a new protease, designated MBP-associated serine protease (MASP) which is required for complement activation by MBP. We have cloned the cDNA that encodes this protease and found that the deduced amino acid sequence contains an epidermal growth factor-like domain, two short consensus repeats and a serine protease domain. The overall structure of MASP is similar to serine proteases of the first complement component complex, C1r-C1s. Unlike C1r-C1s, however, MASP has a histidine loop structure common to many serine proteases such as trypsin and chymotrypsin. The MASP gene was mapped on the long arm of chromosome 3 which is different from C1r-C1s as well as from trypsin and chymotrypsin. These findings suggest that MASP may have emerged prior to C1r-C1s from a common ancestor. This implies that MBP-MASP, a complex of lectin and serine protease, presumably evolved prior to adaptive immune recognition involving antibody and the classical complement pathway.
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PMID:Molecular characterization of a novel serine protease involved in activation of the complement system by mannose-binding protein. 801 3

M6 protein of Streptococcus pyogenes binds directly to HEp-2 cell surfaces and helps to mediate bacterial adhesion. Two epithelial cell receptors for M protein were identified as 97- and 205-kDa glycoproteins. Purified recombinant M6 protein (rM6) showed a dose-dependent and saturable binding to isolated HEp-2 membranes in an enzyme immunoassay. The HEp-2 cell receptors were selectively denatured by pretreatment of isolated membranes at 80 degrees C or with chymotrypsin; binding activity for rM6 was reduced 83 and 80%, respectively. Pretreatment of the HEp-2 membranes with neuraminidase-N-glycosidase, neuraminidase-O-glycosidase, alpha-L-fucosidase, or Ulex lectin caused 33, 42, 73, and 80% reduction of rM6 binding, respectively. Quantitative analysis of HEp-2 cells pretreated with alpha-L-fucosidase showed that the 97- and 205-kDa glycoproteins lost 70 and 62% of their abilities to bind M6 protein and that 33% of the HEp-2 cell's ability to bind whole streptococci was also lost. These results indicated that binding of M6 protein to HEp-2 cell surfaces is highly selective for certain fucose-containing oligosaccharides on these glycoproteins.
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PMID:Streptococcal M6 protein binds to fucose-containing glycoproteins on cultured human epithelial cells. 813 33


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